Audio cables, including coaxial cables and the like used for the reproduction and amplification of sound in musical instruments, are subject to three hard-to-detect malfunctions: short circuit, open conductor, and open shield. Short circuits occur when polyvinyl chloride or nylon cables, for example, become cracked. In other cases, the center conductor or shield element of the ground conductor might become broken due to rough handling, or when the cables are unplugged with too much force. In many instances, only the slightest injury to a cable will be sufficient to alter its performance. Yet, such damage will not be apparent to the naked eye, and it will be necessary to electrically test the cable. An increasing number of audio cables utilize molded leads, in which a non-removable plastic covers the cable lead, making it impossible to check a connection without ruining the lead itself.
Malfunctioning cables, whether those found in musical instruments or in other sound systems, have previously been tested either by taking apart the lead and visually checking it, or by the use of self-enclosed adapters. Visual observation of the connections obviously requires physical opening of the connection, which, as noted, is especially unsatisfactory where molded cables are used. The self-enclosed adapter requires that the cable to be tested be taken out of the system, cut off at the end and run through the adapter. When the specific malfunction is determined, it is then necessary to prepare new cables, along with new jacks, to replace those on the tested cable. New jacks are required since there is not efficient way to remove them prior to such tests. The entire testing operation is thus expensive, due to the need for replacement of both cables and jacks, and unnecessarily elaborate and time consuming.